Components myofibril Flashcards
Fibers are long and cylindrical, Are huge cells– diameter is 10–100µm, Length– several centimeters to dozens of centimeters
Skeletal muscle fiber
Each cell formed by fusion of embryonic cells is called
Mysoblast
Cells are multinucleate, Nuclei are peripherally located
Skeletal muscle fiber
Long rods within cytoplasm, Make up 80% of the cytoplasm, Are a specialized contractile organelle found in muscle
tissue
Myofibrils
A long row of repeating segments called _________
Sacromeres
boundaries of each sarcomere
Z disc or line
run the entire length of an A band
Thick filaments
run the length of the I band and
partway into the A band
Thin filaments
coin-shaped sheet of proteins that anchors the thin filaments and connects myofibrils to one another
Z disc
lighter midregion where filaments do not overlap.
H-Zone
line of protein myomesin that holds adjacent thick filaments together
M-Line
2 interwoven, heavy polypeptide chains
Myosin tails
2 smaller, light polypeptide chains that act as cross bridges during contraction
Myosin heads
a spring-like molecule in sarcomeres
Titin
A calcium regulated protein in muscle tissue occurring in three subunits with tropomyosin
Troponin
Any of a group of muscle proteins that bind to molecules of actin and troponin to regulate the interaction of actin and myosin
Tropomyosin
Functions in the regulation of intracellular Ca2+
levels
Sarcoplasmic reticulum
Continuous with the sarcolemma
T tubules
Network of smooth endoplasmic reticulum
surrounding each myofibril
Sarcoplasmic reticulum
Pairs of terminal cisternae form perpendicular cross channels
Sarcoplasmic reticulum
Penetrate the cell’s interior at each A band–I band
junction
T tubules
Associate with the paired terminal cisternae to form
triads that encircle each sarcomere
T tubules
